一氧化氮（NO）对植物的生理和病理功能

介绍了NO在植物抑御病害及种子萌发、叶片生长、果实成熟、胁迫响应等过程中的作用及其机制。     

Physiological and Pathological Functions of Mechanosensitive Ion Channels

Rapid sensation of mechanical stimuli is often mediated by mechanosensitve ion channels. Their opening results from conformational changes induced by mechanical forces. It leads to membrane permeation of selected ions and thereby to electrical signaling. Newly identified mechanosensitive ion channels are emerging at an astonishing rate, including some that are traditionally assigned for completely different functions. In this review, we first provide a brief overview of ion channels that are known to play a role in mechanosensation. Next, we focus on three representative ones, including the transient receptor potential channel V4 (TRPV4), Kv1.1 voltage-gated potassium (Kv) channel, and Piezo channels. Their structures, biophysical properties, expression and targeting patterns, and physiological functions are highlighted. The potential role of their mechanosensation in related diseases is further discussed. In sum, mechanosensation appears to be achieved in a variety of ways by different proteins and plays a fundamental role in the function of various organs under normal and abnormal conditions.     

细胞外基质与基质金属蛋白酶

细胞外基质（ECM）是存在于细胞之间的动态网状结构,由胶原、蛋白聚糖及糖蛋白等大分子物质组成.这些大分子物质可与细胞表面上的特异性受体结合,通过受体与细胞骨架结构直接发生联系或触发细胞内的一系列信号传导而引起不同的基因表达,从而导致细胞的生长和分化.作为降解ECM成分最重要的酶-基质金属蛋白酶（MMPs）及其组织抑制因子(TIMPs)在这一过程中起着非常重要的作用.MMPs是一类依赖金属离子锌并以ECM成分为水解底物的蛋白水解酶.其在转录水平的表达受到生长因子、细胞因子及激素等因素的严格调控,在蛋白质水平其活性也受到其激活剂和抑制剂的调节. MMPs通过对ECM成分的水解来影响其降解与重组的动态平衡而参与多种细胞的生理和病理过程.     

基质金属蛋白酶及其抑制剂

基质金属蛋白酶（matrix metalloproteinases,MMP)是降解细胞外基质成分的主要酶类,参与很多重要的生理和病理过程。MMP具有典型的多结构组成,MMP活性在基因转录,酶原激活和内源性抑制等方面受到严重调控,调控的紊乱将导致肿瘤扩散和转移,风湿性关节炎等重大疾病的发生,因此MMP成为治疗这些疾病的理想的药物作用靶点,寻找高亲和性,高选择以及高生物利用度的MMP抑制剂成为一项有意义的工作。     

Signaling Functions of Free Radicals Superoxide &; Nitric Oxide under Physiological &; Pathological Conditions

Superoxide and nitric oxide are ubiquitous physiological free radicals that are responsible for many pathological disorders. Both radicals by themselves are relatively harmless but are the precursors of many toxic species such as peroxy and hydroxyl radicals, hydrogen peroxide, and peroxynitrite. However, it has been shown now that both superoxide and nitric oxide are also able to perform important signaling functions in physiological and pathophysiological processes. Wrongly named “superoxide,” the radical anion of dioxygen is not a super-oxidant but the strong super-nucleophile, an efficient catalyst of heterogenic nucleophilic reaction. Due to this, superoxide plays an important role in many enzymatic processes such as the phosphorylation and activation of numerous protein kinases. On the other hand, superoxide inhibits the activation of phosphatases, the enzymes catalyzed by dephosphorylation of protein kinases. We suggest that superoxide catalyzes these enzymatic processes as a result of its nucleophilic properties. Another important physiological function of superoxide and nitric oxide is their competition for the interaction with mitochondrial cytochrome c oxidase. Disturbance of superoxide/nitric oxide balance leads to the dysfunction of mitochondria and the enhancement of apoptosis and oxidative stress, which are primary causes of various pathological disorders and aging. In conclusion, interplay between superoxide and nitric oxide, one of major factors of aging development, is considered.     

基质金属蛋白酶对肿瘤细胞生物学行为调节

近年,对于基质金属蛋白酶(matrix metalloproteinases,MMPs)与肿瘤发生发展的关系有了新的诠释,MMPs的功能已不仅限于通过降解细胞外基质来促进肿瘤的侵袭和转移,它们还可通过水解生长因子、黏附分子、受体等非基质蛋白而触发一系列生物学效应,调节肿瘤的生长、分化、凋亡以及肿瘤的血管生成和免疫逃避。重新认识MMPs的功能,将有助于设计以MMPs为靶标的新型抗肿瘤药物。     

The Biochemical,Biological, and Pathological Kaleidoscope of Cell Surface Substrates Processed by Matrix Metalloproteinases

ABSTRACT

Matrix metalloproteinases (MMPs) constitute a family of more than 20 endopeptidases. Identification of specific matrix and non-matrix components as MMP substrates showed that, aside from their initial role as extracellular matrix modifiers, MMPs play significant roles in highly complex processes such as the regulation of cell behavior, cell-cell communication, and tumor progression. Thanks to the comprehensive examination of the expanded MMP action radius, the initial view of proteases acting in the soluble phase has evolved into a kaleidoscope of proteolytic reactions connected to the cell surface. Important classes of cell surface molecules include adhesion molecules, mediators of apoptosis, receptors, chemokines, cytokines, growth factors, proteases, intercellular junction proteins, and structural molecules. Proteolysis of cell surface proteins by MMPs may have extremely diverse biological implications, ranging from maturation and activation, to inactivation or degradation of substrates. In this way, modification of membrane-associated proteins by MMPs is crucial for communication between cells and the extracellular milieu, and determines cell fate and the integrity of tissues. Hence, insights into the processing of cell surface proteins by MMPs and the concomitant effects on physiological processes as well as on disease onset and evolution, leads the way to innovative therapeutic approaches for cancer, as well as degenerative and inflammatory diseases.     

TRPM7生理病理学功能及其小分子调节剂的发现

TRPM7（transient receptor potential melastatin 7）通道属于TRPM亚家族，是一种具有离子通道结构域和激酶结构域的双功能跨膜蛋白。作为非选择性阳离子通道，TRPM7可通透Ca²⁺、Mg²⁺、Zn²⁺、Na⁺、K⁺等和其他微量金属离子。TRPM7在人体各组织广泛表达，参与Mg²⁺的稳态调控、细胞增殖、分化、黏附和迁移等生理过程。临床上，TRPM7功能紊乱与神经退行性疾病、中风、癌症等多种疾病关系密切。本文主要综述TRPM7通道在生理、病理及小分子调节剂方面的研究进展，为相关疾病的药物开发提供新的思路。     

Matrix Metalloproteinases and Cellular Fibrinolytic Activity

Several molecular interactions between the matrix metalloproteinase (MMP) and the plasminogen/plasmin (fibrinolytic) system may affect cellular fibrinolysis. MMP-3 (stromelysin-1) specifically hydrolyzes urokinase (u-PA), yielding a 17 kD NH₂-terminal fragment containing the functionally intact receptor (u-PAR)-binding sequence and a 32 kD COOH-terminal fragment containing the intact serine proteinase domain. MMP-3 generates an angiostatin like fragment (containing kringles 1-4 with the cellular binding domains) from plasminogen. Treatment with MMP-3 of monocytoid THP-1 cells saturated with bound plasminogen, resulted in a dose-dependent reduction of the amount of u-PA-activatible plasminogen. Treatment with MMP-3 of cell-bound u-PA, in contrast, did not alter cell-associated u-PA activity. These data thus indicate that MMP-3 may downregulate cell-associated plasmin activity by decreasing the amount of activatible plasminogen, with out affecting cell-bound u-PA activity. MMP-3 also specifically interacts with the main inhibitors of the fibrinolytic system. Thus, MMP-3 specifically hydrolyzes human ₂-antiplasmin (₂-AP), the main physiological plasmin inhibitor. ₂-AP cleaved by MMP-3 no longer forms a stable complex with plasmin and no longer interacts with plasminogen. Cleavage and inactivation of ₂-AP by MMP-3 may constitute a mechanism favoring local plasmin-mediated proteolysis. Furthermore, MMP-3 specifically hydrolyzes and inactivates human plasminogen activator inhibitor-1 (PAI-1). Stable PAI-1 bound to vitronectin is cleaved and inactivated by MMP-3 in a comparable manner as free PAI-1; the cleaved protein, however, does not bind to vitronectin. Cleavage and inactivation of PAI-1 by MMP-3 may thus constitute a mechanism decreasing the antipro teolytic activity of PAI-1 and impairing the potential inhibitory effect of vitronectin-bound PAI-1 on cell adhesion and/or migration. These molecular interactions of MMP-3 with enzymes, substrates and inhibitors of the fibrinolytic system may thus play a role in the regulation of (cellular) fibrinolysis. Furthermore, the temporal and topographic expression pattern of MMP components, as well as studies in gene-deficient mice, suggest a functional role in neointima formation after vascular injury.     

基质金属蛋白酶在心肌缺血再灌注损伤中的作用

肌缺血再灌注损伤是指缺血心肌组织在恢复血流供给后,其细胞代谢功能障碍及结构破坏反而加重的现象,主要表现在心肌收缩与舒张功能障碍、血管内皮功能障碍、微循环血流紊乱、细胞代谢失调、电解质平衡紊乱、细胞凋亡与坏死等,并伴随着氧自由基的大量产生和毒性损伤以及炎症反应的激活,是一个极其复杂的病理过程。基质金属蛋白酶(MMPs)及其组织抑制物(TIMPs)是心肌组织中多种细胞分泌的内源性细胞因子,其作用涵盖了细胞外基质降解、炎症反应激活、调节血管功能、影响细胞凋亡与存活等众多病理生理过程,而这些过程均在心肌缺血再灌注损伤中发挥着重要的作用。     

Matrix Metalloproteinases of Normal Human Tissues

This review considers biochemical properties of the family of matrix metalloproteinases (MMPs) of normal human tissues and the involvement of these enzymes in morphogenesis. Four main MMP subfamilies are characterized, and a group of other MMPs is described. Data on mechanisms of activation and inhibition of MMPs in certain tissues during various physiological processes (embryogenesis, angiogenesis, tissue growth and involution) are considered. Information about tissue inhibitors of MMP is presented, and the ability of these inhibitors to regulate the activity of MMPs is analyzed.     

CD147、基质金属蛋白酶与动脉粥样硬化

CD147分子是细胞外基质金属蛋白酶（MMP）的诱导剂,在多种肿瘤细胞和组织中高表达,通过诱导MMP的分泌促进肿瘤的侵袭和转移。MMP在动脉粥样硬化的发生、发展和斑块破裂等心血管并发症的发生中起重要作用。论述了粥样斑块中CD147的表达、CD147对MMP的调控,以及MMP活化对斑块的形成、破裂、引发心肌梗死等急性心血管事件的关联性。     

基质金属蛋白酶与中枢神经系统感染

基质金属蛋白酶(MMPs)是一组合锌的能降解细胞外基质的中性蛋白酶家族.目前认为MMPs尤其是明胶酶(MMP-2,MMP-9)与中枢神经系统感染关系密切.通常它们以酶原的形式存在,一旦活化,则迅速攻击血脑屏障,降解基底膜的一些基质蛋白,破坏内皮细胞的紧密连接蛋白,促进脑水肿的形成和炎细胞的浸润.近年来研究发现,中枢神经系统感染后MMPs表达增加.导致血脑屏障损害及血管源性脑水肿,并参与中枢神经系统免疫反应,促进感染的病理生理过程.     

基质金属蛋白酶在心肌缺血再灌注损伤中的作用

肌缺血再灌注损伤是指缺血心肌组织在恢复血流供给后,其细胞代谢功能障碍及结构破坏反而加重的现象,主要表现在心肌收缩与舒张功能障碍、血管内皮功能障碍、微循环血流紊乱、细胞代谢失调、电解质平衡紊乱、细胞凋亡与坏死等,并伴随着氧自由基的大量产生和毒性损伤以及炎症反应的激活,是一个极其复杂的病理过程。基质金属蛋白酶（MMPs）及其组织抑制物（TIMPs）是心肌组织中多种细胞分泌的内源性细胞因子,其作用涵盖了细胞外基质降解、炎症反应激活、调节血管功能、影响细胞凋亡与存活等众多病理生理过程,而这些过程均在心肌缺血再灌注损伤中发挥着重要的作用。     

生理病理状态下线粒体合成ATP动态调控机制

线粒体是细胞的代谢中心之一,不仅产生大量的ATP为细胞提供能量,还参与多种生物分子（例如核酸、氨基酸、胆固醇和脂肪酸）合成及代谢废物的处理。ATP是细胞重要的“能源货币”,是能量载体和信号分子,参与调节细胞的各种生命活动。动物与人在激烈运动时,ATP消耗速率增加数十倍,但细胞内的ATP仍维持在“设定点”水平,不出现降低。因此,传统生理学观点认为,动物细胞内ATP水平保持恒定。但新的研究结果表明,生物细胞内ATP水平存在波动。生理条件下,增加能量物资（糖、脂和氨基酸等）和氧供,促进线粒体ATP合成,可使细胞内ATP水平出现一过性升高。新的研究证明,在肥胖情况下,由于能量物质的过多供应,细胞内ATP水平出现持续性升高,构成代谢紊乱的源头信号。线粒体ATP合成受多种因素影响,如氧化应激、钙超载、缺氧、线粒体膜通透性增加和线粒体DNA突变等。这些因素与疾病条件下细胞内ATP水平持续降低相关,常见的疾病包括阿尔茨海默症、帕金森疾病、精神分裂症、肿瘤、心衰、全身炎症反应综合征等。本综述简要概述线粒体调节细胞内ATP水平的研究进展,重点讨论造成ATP波动的因素、机制及病理生理学意义。     

生理病理状态下线粒体合成ATP动态调控机制

线粒体是细胞的代谢中心之一,不仅产生大量的ATP为细胞提供能量,还参与多种生物分子（例如核酸、氨基酸、胆固醇和脂肪酸）合成及代谢废物的处理。ATP是细胞重要的“能源货币”,是能量载体和信号分子,参与调节细胞的各种生命活动。动物与人在激烈运动时,ATP消耗速率增加数十倍,但细胞内的ATP仍维持在“设定点”水平,不出现降低。因此,传统生理学观点认为,动物细胞内ATP水平保持恒定。但新的研究结果表明,生物细胞内ATP水平存在波动。生理条件下,增加能量物资（糖、脂和氨基酸等）和氧供,促进线粒体ATP合成,可使细胞内ATP水平出现一过性升高。新的研究证明,在肥胖情况下,由于能量物质的过多供应,细胞内ATP水平出现持续性升高,构成代谢紊乱的源头信号。线粒体ATP合成受多种因素影响,如氧化应激、钙超载、缺氧、线粒体膜通透性增加和线粒体DNA突变等。这些因素与疾病条件下细胞内ATP水平持续降低相关,常见的疾病包括阿尔茨海默症、帕金森疾病、精神分裂症、肿瘤、心衰、全身炎症反应综合征等。本综述简要概述线粒体调节细胞内ATP水平的研究进展,重点讨论造成ATP波动的因素、机制及病理生理学意义。     

基质金属蛋白酶和组织金属蛋白酶抑制剂在肾细胞癌组织中的表达

目的:基质金属蛋白酶及组织金属蛋白酶抑制剂在肾细胞癌转移中占有重要的作用,研究肾细胞癌组织中MMP-2、MMP-9、TIMP-1和TIMP-2的表达情况,为肾癌转移的治疗提供理论依据。方法:选取36例肾细胞癌肾组织标本,从相同的肾细胞癌组织及癌旁肾组织获得对照样本,均进行根治性肾切除手术切除。肿瘤分期按TNM分期标准。为了统计评估,肿瘤1期和2期为低级,3期以上为高级。RT-PCR检测肿瘤和正常组织中的MMP-2、MMP-9、TIMP-1和TIMP-2的表达。结果:不同样本MMPs和TIMPs表达水平各不相同。肾细胞癌组织中MMP-2、MMP-9、TIMP-1、TIMP-2在肾细胞癌中的表达明显高于正常肾组织(P0.05)。在肾细胞癌的肿瘤分期方面,MMP-2与MMP-9和肿瘤的分期显著相关,随着肿瘤分期的增加,MMP-2与MMP-9的表达明显升高(P0.05),而TIMP-1与TIMP-2与肿瘤的分期无关。结论:肾细胞癌组织中TIMP-2、MMP-2,MMP-9,TIMP-1的mRNA表达显著高于正常肾组织,抑制MMPS的表达将成为治疗肾细胞癌转移的新的方向。     

Detection of Functional Matrix Metalloproteinases by Zymography

Matrix metalloproteinases (MMPs) are zinc-containing endopeptidases. They degrade proteins by cleavage of peptide bonds. More than twenty MMPs have been identified and are separated into six groups based on their structure and substrate specificity (collagenases, gelatinases, membrane type [MT-MMP], stromelysins, matrilysins, and others). MMPs play a critical role in cell invasion, cartilage degradation, tissue remodeling, wound healing, and embryogenesis. They therefore participate in both normal processes and in the pathogenesis of many diseases, such as rheumatoid arthritis, cancer, or chronic obstructive pulmonary disease^1-6. Here, we will focus on MMP-2 (gelatinase A, type IV collagenase), a widely expressed MMP. We will demonstrate how to detect MMP-2 in cell culture supernatants by zymography, a commonly used, simple, and yet very sensitive technique first described in 1980 by C. Heussen and E.B. Dowdle^7-10. This technique is semi-quantitative, it can therefore be used to determine MMP levels in test samples when known concentrations of recombinant MMP are loaded on the same gel¹¹.Solutions containing MMPs (e.g. cell culture supernatants, urine, or serum) are loaded onto a polyacrylamide gel containing sodium dodecyl sulfate (SDS; to linearize the proteins) and gelatin (substrate for MMP-2). The sample buffer is designed to increase sample viscosity (to facilitate gel loading), provide a tracking dye (bromophenol blue; to monitor sample migration), provide denaturing molecules (to linearize proteins), and control the pH of the sample. Proteins are then allowed to migrate under an electric current in a running buffer designed to provide a constant migration rate. The distance of migration is inversely correlated with the molecular weight of the protein (small proteins move faster through the gel than large proteins do and therefore migrate further down the gel). After migration, the gel is placed in a renaturing buffer to allow proteins to regain their tertiary structure, necessary for enzymatic activity. The gel is then placed in a developing buffer designed to allow the protease to digest its substrate. The developing buffer also contains p-aminophenylmercuric acetate (APMA) to activate the non-proteolytic pro-MMPs into active MMPs. The next step consists of staining the substrate (gelatin in our example). After washing the excess dye off the gel, areas of protease digestion appear as clear bands. The clearer the band, the more concentrated the protease it contains. Band staining intensity can then be determined by densitometry, using a software such as ImageJ, allowing for sample comparison.